GRB 221006A
GCN Circular 32742
Subject
MAXI GRB 221006A: Redshifts of the possible host galaxies
Date
2022-10-13T19:01:48Z (3 years ago)
From
C. C. Thoene at HETH/IAA-CSIC <christina.thoene@gmail.com>
P. A. C. Cunha (Univ. do Porto/CAUP), G. Ma (DAWN/NBI), R. O���Rourke Brogan
(AIP), C. C. Thoene (ASU-CAS), A. de Ugarte Postigo (OCA, Nice), D. A. Kann
(Goethe Univ.), J. F. Agui Fernandez (IAA-CSIC), L. Izzo (DARK/NBI), J.P.U.
Fynbo (DAWN/NBI), N. R. Tanvir (Univ. Leicester), M. Blazek (Prague) and D.
Garcia Alvarez (GTC) report:
We observed the possible host galaxies of the MAXI GRB (GCN 32626, Mikhara
et al) underlying the candidate afterglow at RA 22:28:58.99, DEC
+15:42:49.6 (GCN 32628, Sbarufatti et al., confirmed to be fading in GCN
32731, Sbarufatti et al.), which we already reported in GCN 32710,
(O���Rourke Brogan et al.). Observations were obtained with OSIRIS at the
10.4m GTC telescope in La Palma starting on Oct. 10, 2022 at 20:10 UT with
a total exposure time of 3x600s using the R1000R grism (5100-10100��) and a
1 arcsec slit aligned across both putative hosts.
We clearly detect the traces of both galaxies in the combined spectrum and
determine redshifts of z=0.731 for G1 and z=0.464 for G2 based on emission
lines of [OII], [OIII] Hb and Ha. Based on the distance from the X-ray
afterglow candidate we determined G1 to be the likely host of GRB 221006A
(GCN 32710, O���Rourke Brogan et al.) and hence assume a redshift of z=0.731
for its possible host galaxy.
We acknowledge two very enjoyable weeks at the NEON observing school during
which these follow-up observations were obtained.
GCN Circular 32731
Subject
GRB 221006A: Swift-XRT afterglow detection
Date
2022-10-13T08:31:05Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B. Sbarufatti (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has conducted further observations of the field of the
MAXI-detected burst GRB 221006A (Mihara et al. GCN Circ. 32626). The
observations now extend from T0+37.8 ks to T0+595.5 ks.
Of the sources reported by Sbarufatti et al. (GCN Circ. 32628), "Source
2" is fading with >3-sigma significance, and is therefore likely the
GRB afterglow. Using 1256 s of PC mode data and 2 UVOT images, we find
an enhanced XRT position (using the XRT-UVOT alignment and matching
UVOT field sources to the USNO-B1 catalogue): RA, Dec = 337.24578,
+15.71379 which is equivalent to:
RA (J2000): 22h 28m 58.99s
Dec(J2000): +15d 42' 49.6"
with an uncertainty of 3.2 arcsec (radius, 90% confidence). This
position is 4.8 arcmin from the MAXI position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.01 (+0.34, -0.25).
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021521.
The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00108.
This circular is an official product of the Swift-XRT team.
GCN Circular 32710
Subject
Afterglow limits of GRB 221006A from OHP
Date
2022-10-12T22:49:00Z (3 years ago)
From
C. C. Thoene at HETH/IAA-CSIC <christina.thoene@gmail.com>
R. O���Rourke Brogan (AIP), P. A. C. Cunha (Univ. do Porto/CAUP), G. Ma
(DAWN/NBI) and C. C. Thoene (ASU-CAS) report:
We observed the field of the MAXI GRB 221006A (GCN 32626, Mikhara et al;
GCN 32628, Sbarufatti et al.) using the 1.2m telescope at the Observatoire
de l���Haute Provence. Observations started on Oct. 06, 2022 at 20:49 UT,
~20h after the GRB under nearly full Moon conditions.
In a combined exposure of 2600s in R-band we do not detect a counterpart at
any of the positions of the three possible candidates (Source 1: RA
22:29:24.52, DEC +15:38:02.8; Source 2: RA 22:28:58.99, DEC +15:42:49.6;
Source 3: RA 22:29:23.07, DEC +15:41:38.6) down to a limiting magnitude of
R = 22 mag (3 sigma).
At the position of source 2, confirmed to be fading with a significance of
4.6 sigma (https://www.swift.ac.uk/xrt_products/TILED_GRB00108/), there are
two underlying galaxies also present in the SDSS, which we call G1 and G2.
Our image shows a combined magnitude of R=21.2 +/- 0.4 for the two
galaxies. The objects show no evidence of excess emission, which is
consistent with our upper limit. G1 has a distance of 0.5 arcsec and G2 of
3.5 arcsec from the X-ray candidate afterglow, making G1 the likely host of
GRB 221006A.
We thank the NEON observing school and the support of the 1.2m telescope
operator Stephane Favard for obtaining these data.
GCN Circular 32682
Subject
GRB 221006A: Swift ToO observations
Date
2022-10-11T11:26:14Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the MAXI GRB 221006A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021524
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the MAXI event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 32674
Subject
GRB 221006A: CALET Gamma-Ray Burst Monitor detection
Date
2022-10-11T05:22:49Z (3 years ago)
From
Yuta Kawakubo at Louisiana State U./CALET <kawakubo1@lsu.edu>
N. Cannady (GSFC/UMBC), A. Yoshida, T. Sakamoto,
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), Y. Asaoka (ICRR), S. Torii, Y. Akaike,
K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 221006A (MAXI/GSC detection: Mihara et al.,
GCN Circ. 32626) was marginally detected in the ground analysis
of the CALET Gamma-ray Burst Monitor (CGBM) data near the
MAXI trigger time at 00:57:09 UTC on October 6, 2022.
The burst signal was seen by only HXM detectors.
The burst light curve shows a faint signal which starts at T+0.8 sec,
peaks at T+9.8 sec and ends at T+26.8 sec. The T90 and T50
durations measured by the HXM2 data are 24.0 +/- 2.0 sec and
14.0 +/- 2.0 sec (7-100 keV), respectively. The highest significance
during the burst is 4.6 sigma at T+15.8 sec with HXM2 data in the 7 - 10 keV band.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1349052973/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 32628
Subject
GRB 221006A: Swift-XRT observations
Date
2022-10-07T14:56:27Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B. Sbarufatti (INAF-OAB), J. D. Gropp (PSU), S. Dichiara (PSU), J.A.
Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 221006A (Mihara et al. GCN Circ. 32626) in a series of
observations tiled on the sky. The total exposure time is 1.9 ks,
distributed over 3 tiles; the maximum exposure at a single sky location
was 992 s. The data were collected between T0+37.6 ks and T0+39.8 ks,
and are entirely in Photon Counting (PC) mode.
Three uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:
Source 1:
RA (J2000.0): 337.3524 = 22:29:24.58
Dec (J2000.0): +15.6341 = +15:38:02.8
Error: 12.1 arcsec (radius, 90% conf.)
Count-rate: 0.0104 [+0.0063, -0.0045] ct s^-1
Distance: 262 arcsec from MAXI position.
Source 2:
RA (J2000.0): 337.2458 = 22:28:58.99
Dec (J2000.0): +15.7138 = +15:42:49.6
Error: 3.2 arcsec (radius, 90% conf. [Enhanced position])
Count-rate: 0.0401 [+0.0076, -0.0070] ct s^-1
Distance: 287 arcsec from MAXI position.
Flux: (1.67 [+0.32, -0.29])e-12 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Source 3:
RA (J2000.0): 337.3461 = 22:29:23.07
Dec (J2000.0): +15.6941 = +15:41:38.6
Error: 8.2 arcsec (radius, 90% conf.)
Count-rate: 0.0106 [+0.0043, -0.0034] ct s^-1
Distance: 70 arcsec from MAXI position.
Flux: (2.00 [+0.81, -0.64])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00108.
This circular is an official product of the Swift-XRT team.
GCN Circular 32627
Subject
GRB 221006A: Tiled Swift observations
Date
2022-10-06T11:25:32Z (3 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 221006A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00108
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
GCN Circular 32626
Subject
GRB 221006A: MAXI/GSC detection
Date
2022-10-06T02:15:28Z (3 years ago)
From
Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>
T. Mihara (RIKEN), M. Nakajima, H. Negoro (Nihon U.), W. Iwakiri (Chuo U.),
K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.),
T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, A. Yoshida (AGU),
Y. Tsuboi, J. Kohara (Chuo U.),
M. Shidatsu, M. Iwasaki (Ehime U.),
N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech),
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA),
Y. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, K. Inaba (Kyoto U.),
M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray
transient source at 2022-10-06T00:57:09 UT.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (337.328 deg, 15.703 deg) = (22 29 18, +15 42 10) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.11 deg and 0.09 deg, respectively.
The roll angle of long axis from the north direction is 26.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 909 +- 81 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 10/5 23:24 UT
with an upper limit of 20 mCrab.